There are lots of folding wing 2-3 seat biplane naval aircraft, but no single seaters? Presumably they're sufficiently compact for stowage and the added weight of folding mechanisms is best avoided. But no examples whatsoever?
The first folding wing single seat carrier aircraft of any configuration was the French Dewoitine D.373.
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Which ignores the single seat Sopwith T.1 Cuckoo torpedo bomber. First flight June 1917. First 100 production aircraft ordered Feb 1918 (50 each from Pegler of Doncaster and Blackburn). First delivery from Blackburn July 1918 followed by Pegler in Oct. Entered service with the Torpedo Aeroplane School at East Fortune, East Lothian Scotland (now home to the National Museum of Flight) then with 185 squadron RAF on its formation on 19 Oct 1918. These were photographed aboard the first flush decked carrier, HMS Argus (completed Sept 1918) the following month.
The plan had been for aircraft from Argus to carry out a torpedo attack on the German High Seas Fleet in its home ports before the end of 1918. The Armistice put an end to these plans.
Cuckoos in Argus' hangar Nov/Dec 1918.
The Avro Bison of 1921, a 3/4 seat carrier borne fleet spotter-recce aircraft also had folding wings. Blackburn Ripon 2 seater of 1926 was another.
In terms of early fighters (or "scouts" as they were referred to in the early days) with folding wings, there was the Beardmore W.B. III of 1918. This was a derivative of the Sopwith Pup built by William Beardmore & Co of Dalmuir, Dunbartonshire. Beardmore had been building Pups for the RNAS under licence, but the folding wings were designed by a Mr G Tilghman Richards of Beardmore. On 31 Oct 1918, 55 are recorded as being in service with the RAF, including 18 with the Grand Fleet.
Two versions built - one with folding undercarriage S.B.3F and one with jettisonable undercarriage S.B.3D.
And here all folded up ready for the hangar